I do this by putting the PDFs in the same git repo as my ledger file, and then adding a filename to the entry as metadata: 2015/11/04 * (12345) Walgreens

I do this by putting the PDFs in the same git repo as my ledger file, and then adding a filename to the entry as metadata: 2015/11/04 * (12345) Walgreens ; receipt: /receipts/12345.pdf Expenses:Medical:RX $10.00 Liabilities:Credit Card It isn't an attachment, strictly speaking, but you can get at it with scripts and such.